Sputtering target producing few particles, backing plate or sputtering apparatus and sputtering method producing few particles

ABSTRACT

A sputtering target producing few particles, a backing plate or a sputtering apparatus, and a sputtering method producing few particles. An arc-spraying coating film and a plasma-spraying coating film over the former are formed on the sputtering target, a backing plate, or another surface in the sputtering apparatus, where an unwanted film might be formed. Thus a deposit is prevent from separating/flying from the target, backing plate, or another surface where an unwanted film might be formed in the sputtering apparatus.

TECHNICAL FIELD

[0001] The present invention relates to a sputtering target producingfew particles during deposition, a backing plate or sputtering apparatusand a sputtering method producing few particles.

BACKGROUND ART

[0002] In recent years, the sputtering method capable of easilycontrolling the film thickness and components is being widely used asone of the deposition methods of materials for electronic and electriccomponents.

[0003] This sputtering method makes the targets formed of a positiveelectrode and a negative electrode face each other and applies a highvoltage between these substrates and the target under an inert gasatmosphere in order to generate an electric field, and employs thefundamental principle in which plasma is formed upon the atoms ionizedat such time colliding with the inert gas, the positive ions within thisplasma colliding with the target (negative electrode) surface anddischarging the atoms structuring the target, whereby the film is formedby the discharged atoms adhering to the opposing substrate surface.

[0004] Upon forming a thin film with this sputtering method, the problemof the production of particles has been attracting attention. In termsof particles caused by the target during the sputtering method, forexample, the thin film is deposited within the walls of the thin filmforming device and all over the materials and the like therein, inaddition to the substrate, when a target is sputtered. Faces and sidefaces other than the erosion portion of the target are no exceptions,and the deposits of sputtered particles have been observed.

[0005] And, flakes separating from such materials and the like withinthe thin film forming device directly flying on the substrate surface isconsidered to be one of the major causes for the production ofparticles.

[0006] Moreover, since the side face of the target is not generallyfacing the plasma directly, there are not that many problems regardingthe production of particles from the side face. Thus, conventionally,there were numerous examples wherein measures are taken for the centerpart of the target and the non-erosion portion of the peripheral edge.Nevertheless, there is a trend toward the overall face of the sputteringface being sputtered in order to improve the target usage efficiency,and such measures may adversely increase the particles.

[0007] Recently, while the degree of integration of LSI semiconductordevices has increased (16M bit, 64M bit and even 256M bit) on the onehand, it is also becoming miniaturized with the wiring width being lessthan 0.25 ìm in some cases, and problems such as the disconnection andshort circuit of wiring due to the foregoing particles now occur morefrequently.

[0008] As described above, the production of particles is now even alarger problem pursuant to the advancement of high integration andminiaturization of electronic device circuits.

[0009] Generally, a sputtering target is connected to a backing platehaving a larger measurement with such means as welding, diffusionbonding or soldering. From the perspective of the stabilization ofsputtering, however, the side face of the sputtering target to beconnected to the backing plate is usually formed to have an inclinedface broadening toward such backing plate.

[0010] As publicly known, a backing plate plays the role of cooling thetarget by the back face thereof contacting a coolant, and materials suchas aluminum or copper or the alloys thereof having a favorable thermalconductivity are used.

[0011] The side face of the foregoing sputtering target is not theportion which will erode (become subject to wear) from sputtering.Nonetheless, since it is close to the erosion face of the target, thereis a trend toward the sputtered particles flying during the sputteringoperation further adhering and depositing thereto.

[0012] In general, the erosion face of a sputtering target has a smoothsurface from the turning process, and the foregoing inclined side faceis similarly subject to the turning process.

[0013] Whereas, it has become known the sputtered particles (deposits)once adhered to the inclined side face are separated therefrom onceagain, float, and cause the production of particles.

[0014] Further, it has been observed that, rather than from the vicinityof the flat peripheral erosion face, the separation of such depositsoccurs more often from a location distant therefrom.

[0015] This kind of phenomenon has not necessarily been clearlyunderstood, nor were measures taken therefor. However, the production ofparticles in such locations has also become a major problem in light ofthe demands of the high integration and miniaturization of electronicdevice circuits as described above.

[0016] In order to overcome the foregoing problems, a proposal has beenmade of performing blast processing to the target side face and thebacking plate vicinity and improving the adhesiveness thereby with theanchor effect.

[0017] Nevertheless, in such a case, problems such as the contaminationof goods due to the remnants of the blast materials, separation of theadhered particles deposited on the residual blast materials, andseparation of the adhered film caused by the selective and uneven growththereof would newly arise, and the fundamental issues could not beresolved.

[0018] Further, even upon particularly performing such blast processing,particles tend to be produced due to the differences in the materialsbetween the target side face and the backing plate and the difference inthermal expansion as a result thereof, and the evident differencebetween the materials. And, in such a case, since it is far from theforegoing erosion portion, there is problem in that this will gounnoticed as a cause of the production of particles.

[0019] In consideration of the above, the present inventors previouslyproposed a sputtering target producing few particles (Japanese PatentApplication No. 2000-31477) comprising a sprayed coating having a centerline average roughness of Ra 10 to 20 ìm at least on the side face ofthe sputtering target.

[0020] This technology itself, when compared with conventional methods,yielded an effect of by far preventing the separation of the adheredfilm and suppressing the production of particles. Nevertheless, electricarc spraying or plasma spraying was used for forming the sprayed coatingand, regarding the former, the surface roughness tended to be large withmuch variation and the adhesiveness of the adhered film was uneven,whereas with the latter, the surface roughness tended to be small andthe adhesiveness with the attachment would be inferior since the anchoreffect is low, and satisfactory results could not always be obtained.

[0021] Moreover, this issue of the sprayed coating formed forsuppressing the production of particles is not limited to the targetside face described above, and similar issues are found in the otherfaces of the sputtering target, and in the face to which unnecessaryfilms of equipment within the sputtering apparatus are deposited.

DISCLOSURE OF THE INVENTION

[0022] In light of the foregoing problems, an object of the presentinvention is to obtain a sputtering target, backing plate or sputteringapparatus and a sputtering method capable seeking the improvement in thesprayed coating, and thereby directly preventing the separation andflying of a deposit from the target, backing plate or another surfacewhere an unwanted film might be formed in the sputtering apparatus in amore effective manner.

[0023] In order to achieve the foregoing object, the present inventorsdiscovered that the production of particles within the deposition couldbe efficiently suppressed by improving the sprayed coating process.

[0024] Based on this discovery, the present invention provides:

[0025] 1. A sputtering target, backing plate or sputtering apparatusproducing few particles, characterized in that an arc-spraying coatingfilm and a plasma-spraying coating film over the former are formed onthe sputtering target, backing plate or another surface in thesputtering apparatus where an unwanted film might be formed;

[0026] 2. A sputtering target, backing plate or sputtering apparatusproducing few particles according to paragraph 1 above, characterized incomprising a sprayed coating having a surface roughness of 10 to 20 μmRa;

[0027] 3. A sputtering target, backing plate or sputtering apparatusproducing few particles according to paragraph 1 or paragraph 2 above,characterized in sequentially comprising a sprayed coating along thesputtering target side face or the backing plate face;

[0028] 4. A sputtering target, backing plate or sputtering apparatusproducing few particles according to each of paragraphs 1 to 3 above,characterized in comprising a sprayed coating along the backing platedirection or backing plate face from a side face position slightlydistant than the sputtering face of the sputtering target;

[0029] 5. A sputtering target, backing plate or sputtering apparatusproducing few particles according to each of paragraphs 1 to 4 above,characterized in that aluminum or an aluminum alloy is used as thesprayed coating;

[0030] 6. A sputtering method producing few particles, characterized inthat an arc-spraying coating film and a plasma-spraying coating filmover the former are formed on the sputtering target, backing plate oranother surface in the sputtering apparatus where an unwanted film mightbe formed;

[0031] 7. A sputtering method producing few particles according toparagraph 6 above, characterized in comprising a sprayed coating havinga surface roughness of 10 to 20 μm Ra;

[0032] 8. A sputtering method producing few particles according toparagraph 6 or paragraph 7 above, characterized in sequentiallycomprising a sprayed coating along the sputtering target side face orthe backing plate face;

[0033] 9. A sputtering method producing few particles according to eachof paragraphs 6 to 8 above, characterized in comprising a sprayedcoating along the backing plate direction or backing plate face from aside face position slightly distant than the sputtering face of thesputtering target; and

[0034] 10. A sputtering method producing few particles according to eachof paragraphs 6 to 9 above, characterized in that aluminum or analuminum alloy is used as the sprayed coating.

BEST MODE FOR CARRYING OUT THE INVENTION

[0035] As a method of spraying aluminum or aluminum alloy, there is arcspraying and plasma spraying. Arc spraying and plasma spraying are thesame in principle, and are methods in which arc spraying uses an arc asthe heat source and plasma spraying uses a plasma jet flame to melt thespraying material, which makes the high-temperature melting particlesfly and collide with the material surface, and laminates the same inorder to form a coating.

[0036] Nevertheless, it has been discovered that an extremely largedifference exists upon performing this arc spraying or plasma sprayingon the sputtering target, backing plate or another surface in thesputtering apparatus where an unwanted film might be formed and havingexamined the separation of the coating.

[0037] Upon forming a sprayed coating with only arc spraying, thesurface area of the melting portion of aluminum or aluminum alloy waslarge, separation resistance was worse than expected, and the surfacecondition was one which left concern. And, as a result of performing theactual sputtering, the partial separation of the deposit was observed.

[0038] Contrarily, when forming a sprayed coating with only plasmaspraying, it lacked the surface roughness, the anchor effect was low,the adhesiveness with the adhered film during sputtering was reduced,and, as a result, the particle reduction effects became inferior.

[0039] Thus, upon examining the various possibilities of the sprayingmethod, it has been discovered that by forming an arc spraying coatingfilm and further forming a plasma spraying coating film thereon, asprayed coating having an even and optimum surface roughness against asurface of a fixed surface area can be formed.

[0040] Generally, with plasma spraying, the melting particles havelarger collision energy in comparison to arc spraying, and the surfaceroughness would become small since the melting particles are flattened.

[0041] The major difference between these spraying methods is in theheat source temperature and the flying speed of melting particles. Withplasma spraying, the temperature is approximately 10,000° C. and theflying speed of melting particles is roughly 700 m/sec, and, whereas,with arc spraying, the temperature is approximately 5,000° C. and theflying speed of melting particles is roughly 100 m/sec.

[0042] By utilizing the functions of plasma spraying and arc spraying, aspray coating having a large surface roughness is foremost formed on thematerial surface covered with arc spraying, and plasma spraying isthereafter employed to reduce the surface roughness so as to obtain theoptimum surface roughness.

[0043] It is thereby possible to easily control the surface roughness tobe even and stable.

[0044] Moreover, when performing arc spraying after plasma spraying, thesurface roughness became too large and exceeded the optimum value, andthus not preferable.

[0045] The sprayed coating of the present invention may be formed on thesputtering target, backing plate or another surface in the sputteringapparatus where an unwanted film might be formed. In order to achieve anappropriate anchor effect with this sprayed coating, preferably, asprayed coating having a center line average roughness Ra of 10 to 20 μmis provided.

[0046] This may be easily achieved by performing the foregoing plasmaspraying after the arc spraying. And a superior effect is yielded inthat the production of particles is effectively suppressed.

[0047] For application in targets, for example, the spraying of thepresent invention may be employed in a rectangular or circular target,as well as targets of other shapes. Here, it is also effective to form asprayed coating on the non-erosion portion; that is, the side face ofthe target.

[0048] Although the side faces are often inclined faces, the presentinvention may also be employed in sputtering targets having a structureof perpendicular faces or planar faces successive thereto. The presentinvention includes all of the above.

[0049] Particularly, the production of particles from the target sideface is often overlooked, but it has been observed that the sputteredparticles (deposits) once adhered to the inclined side face areseparated therefrom once again, float, and cause the production ofparticles.

[0050] Furthermore, it has become known that, rather than from thevicinity of the flat peripheral erosion face, the separation of suchdeposits occurs more often from a location distant therefrom. Therefore,the formation of a sprayed coating on such side face is extremely easy,and there is an advantage in that the production of particles can beeffectively suppressed.

[0051] As the material of the sprayed coating, a material of the samequality of material as the target material may be used, or othermaterials may be used, so as long as arc spraying and plasma sprayingmay be performed thereto. Here, the only limitation would be that it isdesirable to use a material that will not contaminate the sputteringthin film to the substrate.

[0052] As described above, since the sprayed coating shows a uniqueanchor effect, this is not particularly limited unless it becomes acause of contamination due to the sprayed coating separates as a resultof the sprayed coating becoming vulnerable.

[0053] As such examples, used may be Ti, Zr, Hf, Nb, Ta, Mo, W, Al, Cu,and alloys or the like with these as the main component.

[0054] Moreover, as the backing plate material, the ordinarily usedcopper, copper alloy, aluminum, aluminum alloy and the like may be used,and there is no limitation. With respect to the sputtering apparatus, itis not particularly necessary to specify a material, and sprayed coatingmay be formed on stainless steel or other material surfaces.

[0055] When the side face of the sputtering target is of an inclinedface, in particular, the present invention may be used for sputteringtargets in which the side face thereof to be connected to the backingplate is broadening toward such backing plate.

[0056] Particularly, with the sprayed coating of the present invention,it is desirable that the sprayed coating is formed successively alongthe sputtering target side face and the backing plate face.

[0057] As described above, there is a trend toward the particles beingproduced due to the differences in the materials between the target sideface and the backing plate and the difference in thermal expansion as aresult thereof, and the evident difference between the materials.Nevertheless, by forming a sprayed coating having a strong anchor effectat this problematic portion, the production of particles may beeffectively prevented.

[0058] The formation of the successive sprayed coatings to the backingplate may be over the entire face in which the target is exposed, or maybe in the vicinity of the connection with the target. The presentinvention includes all of the above. Therefore, it goes without sayingthat the sprayed coating may be formed successively along the sputteringtarget side face, lower planar face and backing plate face.

EXAMPLES

[0059] Next, the Examples and Comparative Examples of the presentinvention are explained. The Examples are mere exemplifications of thepresent invention, and shall not limit the present invention in any way.In other words, modifications and other modes based on the technicalspirit of the present invention shall all be included herein.

Example 1

[0060] A sprayed coating was formed on a stainless plate (SUS304) underthe following conditions.

[0061] (Arc Spraying Conditions)

[0062] Current: 20A

[0063] Voltage: 260V

[0064] Air Pressure: 80 psi

[0065] Wire Used: φ1.6 mm aluminum wire (purity 99.6)

[0066] Wire Feed: 6g/min

[0067] Distance between Spraying Gun and Stainless Plate: 200 mm

[0068] (Plasma Spraying Conditions)

[0069] Current: 750A

[0070] Voltage: 30V

[0071] Ar Gas Pressure: 55 psi

[0072] He Gas Pressure: 50 psi

[0073] Raw Material Feed: 6 g/min

[0074] Distance between Spraying Gun and Stainless Plate: 200 mm

[0075] Raw Material Powder Used: Aluminum powder +5 t magnesium alloypowder (average grain diameter 75 μm)

[0076] Spray Time: Arc spraying 3 sec+plasma spraying 2 sec

Comparative Example 1

[0077] Arc spraying was performed to a stainless plate under thefollowing conditions.

[0078] (Arc Spraying Conditions)

[0079] Current: 20A

[0080] Voltage: 260V

[0081] Air Pressure: 80 psi

[0082] Wire Used: φ1.6 mm aluminum wire (purity 99.6)

[0083] Wire Feed: 6 g/min

[0084] Distance between Spraying Gun and Stainless Plate: 200 mm

[0085] Spray Time: 5 sec

Comparative Example 2

[0086] (Plasma Spraying Conditions)

[0087] Current: 750A

[0088] Voltage: 30V

[0089] Ar Gas Pressure: 55 psi He Gas Pressure: 50 psi

[0090] Raw Material Feed: 6 g/min

[0091] Distance between Spraying Gun and Stainless Plate: 200 mm

[0092] Raw Material Powder Used: Aluminum powder +5% magnesium alloypowder (average grain diameter 75 μm)

[0093] Spray Time: 5 sec

[0094] The sprayed surface area of foregoing Example 1 and ComparativeExamples 1 and 2 was within the range of approximately 150 mm indiameter. The measurement results of the surface roughness of Example 1and Comparative Examples 1 and 2 are shown in Table 1. The surfaceroughness was measured in 10 locations.

[0095] As shown in Table 1, in comparison to Comparative Examples 1 and2, with the arc spraying+plasma spraying of Example 1, if is easy tocontrol the roughness to be the target surface roughness of 10 to 20 ìmRa, and there is minimal variation in the surface roughness. TABLE 1Measurement Results of Surface Roughness (Center Line Surface RoughnessRa (μm)) Comparative Comparative Example Example Example 2 1 16.22 21.3011.80 2 16.87 17.50 10.25 3 15.14 19.50 11.76 4 17.89 23.50 9.80 5 15.5020.17 10.77 6 14.51 18.80 9.90 7 16.40 19.70 10.50 8 17.30 21.20 11.30 917.30 22.30 9.80 10 15.10 19.80 9.20 Average 16.22 20.38 10.41 Standard1.070 1.654 0.960 Deviation

Example 2

[0096] A sprayed coating was formed under the arc spraying+plasmaspraying conditions shown in Example 1 to the side face portion of adiscoid high purity titanium having a diameter of 300 mm and thicknessof 10 mm.

[0097] However, the distance between the spraying gun and work (target)was set to approximately 300 mm, and the sprayed coating thickness wascontrolled by altering the rotation of the work (target) to 50, 60, 70rpm.

[0098] This side face sprayed target was mounted on a sputteringapparatus, and a TiN film was formed with reactive sputtering.Sputtering was performed until the TiN film thickness became 40 ìm, andthe situation of the adhered film was observed.

Comparative Example 3

[0099] Similar to Example 2, a sprayed coating was formed under the arcspraying (only) condition shown in Comparative Example 1 to the sideface portion of a discoid high purity titanium. The distance between thespraying gun and work (target) was set to approximately 300 mm, and thesprayed coating thickness was controlled by altering the rotation of thework (target) to 50, 60, 70 rpm.

[0100] This side face sprayed target was mounted on a sputteringapparatus, and a TiN film was formed with reactive sputtering.Sputtering was performed until the TiN film thickness became 40 μm, andthe situation of the adhered film was observed.

Comparative Example 4

[0101] Similar to Example 2, a sprayed coating was formed under plasmaspraying (only) condition shown in Comparative Example 2 to the sideface portion of a discoid high purity titanium. The distance between thespraying gun and work (target) was set to approximately 300 mm, and thesprayed coating thickness was controlled by altering the rotation of thework (target) to 50, 60, 70 rpm.

[0102] This side face sprayed target was mounted on a sputteringapparatus, and a TiN film was formed with reactive sputtering.Sputtering was performed until the TIN film thickness became 40 ìm, andthe situation of the adhered film was observed.

[0103] The results of Example 2 and Comparative Examples 3 and 4 areshown in Table 2. When forming a coating with the arc spraying+plasmaspraying method of Example 2, separation of the adhered TiN film couldnot be observed in those with the work rotation set to 50, 60 rpm, butthe 70 rpm one with a thin sprayed coating showed separation. It isconsidered that the film thickness of the sprayed coating needs to beroughly 200 μm or more.

[0104] The one to which arc spraying was performed in ComparativeExample 3 had a large surface roughness, the surface condition wasuneven, and separation of the TiN film from such uneven portion wasobserved.

[0105] Moreover, the one to which plasma spraying was performed inComparative Example 4 had a small surface roughness, had an insufficientanchor effect in securely adhering the TiN film, and the separation ofthe TiN film was observed. TABLE 2 Surface Existence of SprayedRoughness Separation Work Film Ra of TIN Film of Rotation ThicknessSprayed Thickness Sputtered (rpm) (μm) Film (μm) (μm) Particles Example2 50 265 15.2 40 No Separation Arc + 60 210 13.8 41 No Plasma SeparationSpraying 70 170 12.6 39 Separation of TiN Film Compara- 50 260 27.8 42Separation of tive TiN Film Example 3 Arc 60 200 24.6 41 Separation ofSpraying TiN Film 70 175 22.6 39 Separation of TiN Film Compara- 50 28010.2 38 Separation of tive TiN Film Example 4 Plasma 60 220 8.4 42Separation of Spraying TiN Film 70 160 6.7 39 Separation of TiN Film

[0106] The surface roughness was measured in a direction of 90 in theperipheral direction with a 5-point average.

[0107] Effect of the Invention

[0108] A superior effect is yielded in that obtained is a sputteringtarget, backing plate or sputtering apparatus and a sputtering methodcapable seeking the improvement in the sprayed coating and forming anarc-spraying coating film and a plasma-spraying coating film over theform, and thereby directly preventing the separation and flying of adeposit from the target, backing plate or another surface where anunwanted film might be formed in the sputtering apparatus in a moreeffective manner.

1. A sputtering target, backing plate or sputtering apparatus producingfew particles, characterized in that an arc-spraying coating film and aplasma-spraying coating film over the former are formed on thesputtering target, backing plate or another surface in the sputteringapparatus where an unwanted film might be formed.
 2. A sputteringtarget, backing plate or sputtering apparatus producing few particlesaccording to claim 1, characterized in comprising a sprayed coatinghaving a surface roughness of 10 to 20 μm Ra.
 3. A sputtering target,backing plate or sputtering apparatus producing few particles accordingto claim 1 or claim 2, characterized in sequentially comprising asprayed coating along the sputtering target side face or the backingplate face.
 4. A sputtering target, backing plate or sputteringapparatus producing few particles according to each of claims 1 to 3,characterized in comprising a sprayed coating along the backing platedirection or backing plate face from a side face position slightlydistant than the sputtering face of the sputtering target.
 5. Asputtering target, backing plate or sputtering apparatus producing fewparticles according to each of claims 1 to 4, characterized in thataluminum or an aluminum alloy is used as the sprayed coating.
 6. Asputtering method producing few particles, characterized in that anarc-spraying coating film and a plasma-spraying coating film over theformer are formed on the sputtering target, backing plate or anothersurface in the sputtering apparatus where an unwanted film might beformed.
 7. A sputtering method producing few particles according toclaim 6, characterized in comprising a sprayed coating having a surfaceroughness of 10 to 20%Lm Ra.
 8. A sputtering method producing fewparticles according to claim 6 or claim 7, characterized in sequentiallycomprising a sprayed coating along the sputtering target side face orthe backing plate face.
 9. A sputtering method producing few particlesaccording to each of claims 6 to 8, characterized in comprising asprayed coating along the backing plate direction or backing plate facefrom a side face position slightly distant than the sputtering face ofthe sputtering target.
 10. A sputtering method producing few particlesaccording to each of claims 6 to 9, characterized in that aluminum or analuminum alloy is used as the sprayed coating.